This invention relates to a compact snowmobile in which a liquid-cooled engine is installed, and more particularly to a radiator arrangement for this type of liquid-cooled engine of a compact snowmobile.
Generally, a snowmobile travels in cold areas, and therefore uses an air-cooled engine. This kind of air-cooled engine, however, has the drawbacks that it generates loud noises during its travel, and that it is likely to be overheated when the snowmobile is idling. It has been contemplated, therefore, to use in the snowmobile a liquid-cooled engine only producing gentle or low sounds and capable of effectively performing the engine cooling even when the snowmobile is idling or operating in a low load condition. As well known, a liquid-cooled engine requires a radiator for cooling the cooling medium, and this radiator occupies a relatively large space. It is, therefore, a very essential problem at what position of the snowmobile the radiator should be placed.
Generally, the snowmobile has an engine room situated at a forward part of the snowmobile body. This engine room is defined by a bottom cover extending toward a forward end of the snowmobile in an upwardly inclined manner and a cowl extending from substantially right above a rear end of the bottom cover toward the forward end of the snowmobile in a downwardly inclined manner. Accordingly, the vertical cross section of the engine room becomes smaller toward the forward end of the snowmobile. At a substantially central part of the engine room an engine is installed, and at one lateral side of the engine an automatic transmission mechanism of V-belt type is placed. In addition, exhaust and intake silencers each having a large capacity are received in the engine room. Even if, in the above-mentioned arrangement, an attempt is made to place the radiator at a forward part of the engine room, the installation of the radiator is difficult because of only a small space being left at said forward part of the engine room. Further, even if the radiator is forcibly installed under such circumstances, the forward end portion of the snowmobile tends to be buried under accumulated snow during its travel and this prohibits a cold wind from being introduced toward the radiator. On the other hand, when the radiator is disposed at a central part of the rear end portion of the engine room, hot air having absorbed the radiator heat is blown directly onto a driver and further a wind passageway must be provided in a manner bypassing the engine at the central part of the engine room to extend up to the radiator. Further, when the radiator is installed on the cowl, a large weight is applied onto the cowl and this disadvantageously results in decreasing the mechanical strength of the cowl.
In this type of snowmobile, it is also of great importance how the above-mentioned wind passageway for guiding a cold wind into the radiator should be provided. That is to say, where an inlet opening of the wind passageway is provided at a lower part of the engine room, there is a fear that the accumulated snow may enter into the wind passageway to prevent the flow of a cold wind. Further, where said inlet opening is provided at a lateral side of the engine room, it becomes difficult for the open air to enter the wind passageway during the travel of the snowmobile.
Since, as above described, various limitations are imposed upon the position at which the radiator and the wind passageway are to be installed or provided, difficulties have been presented in exploiting a practical compact snowmobile having a liquid-cooled engine installed therein.